During various regenerative osseous surgeries in dentistry, a membrane is often placed to block out soft tissue growth and invagination into bone graft sites. This is necessary because bone growth occurs at a slower rate than soft tissue growth during the healing process. By covering the selected bone graft material with a membrane (resorbable or non-resorbable), the faster growing soft tissue is blocked from growing into the graft, thereby allowing the slower growing bone cells to infiltrate into the graft and ideally allow for a greater amount of bone regeneration. Dental bone grafting is most commonly done in association with site development for dental implants but can be done in other applications where bone preservation or regeneration is needed. These applications include, but are not limited to, socket preservation following dental extractions or bone regeneration to correct bone loss related to periodontal disease, trauma, or long term missing teeth.
Typically, after the bone graft has been appropriately placed at the desired site, a membrane is gently placed, using a tissue forceps or college pliers (which is not specifically designed for membrane placement), between gingival tissue (under the periostium) and the bone graft. The membrane can be secured into place with sutures, tacks, or screws if needed. Primary closure is achieved over most membranes although is not always indicated with some non-resorbable membranes.
Membranes are normally provided from the manufacturer in a square, rectangular or oval shape and are cut to a preferred shape for placement. A horizontal peanut shape is effective for placement over grafted extraction sites between two teeth.
Sometimes the space in which the membrane must be placed is quite narrow, which often causes ideal placement to be difficult. As the membrane is placed between the periostium and bone graft, the corners have a tendency to fold up and over toward the periostium, leaving the deeper portions of the graft potentially exposed to soft tissue invagination. Similarly, as flapless and less invasive approaches are becoming more widely advocated, so is this issue of passing a membrane through tight spaces without having the edges fold. Existing tissue forceps, which are currently being used for membrane placement, need significant modification to be made more specific for membrane placement in order to prevent membrane folding on placement.
The gripping and placing other flat, flexible materials such as autogenous connective tissue grafts during oral surgery can also be difficult for similar reasons.